Abstract: A network server includes a communicator connected to a network; and at least one processor configured to communicate, through the communicator, with a user terminal connected to the network. The processor is configured to include or associate content IDs, determined according to one or more requests from the user terminal, in or with a playlist, the content IDs corresponding to content files, respectively, stored in a database; reflect actions of the user terminal, associated with one or more of the content files, on log data sets corresponding to the content IDs; and determine one or more of the content IDs as one or more target IDs to be selectively deleted or excluded from the playlist, on the basis of the log data sets.